RGB Bypass – New Upcoming Design

In collaboration with RetroRGB, I am designing a new version of the Genesis RGB Bypass. This board is a mod for Sega Genesis / Megadrive which improves the video output quality on RGB and removes the jailbars which the Genesis is so notorious for.

Jailbars!

Jailbars are hideous evil vertical lines of alternating darkness easily visible on solid colours displayed on the Sega Genesis. Notice in the image below on the shades of green in the palm tree appear to have vertical stripes through them. These are jailbars and they do not below in the video output but rather appear as an annoyance to video purists.

The Circuit

The circuit on the RGBBypass board I am designing will have two main purposes:

Improved RGB video amplifier through THS7374

Mega Amp

The Mega Amp is a replacement audio circuit for Genesis consoles which aims to put all of the different PCB revisions’ audio quality on the same level. It correctly mixes all of the sound sources and delivers stereo audio (important for Model 1 owners). An important feature of my RGBBypass design is that it will route all signals to a standard Genesis 2 output connector.

Preparing My Test Console

I decided to socket the stock video amplifier, CXA1145, on my test Genesis console. That way, when I go about testing the RGB Bypass board in the future I can simply remove the CXA1145 and restore when testing is over. This will also be great for comparison shots between the existing “jailbarred” video and the improved video output.

Wait for the PCBs to Arrive

The longest step in hardware development is usually the 3-4 week waiting period for chinese PCB manufacturers. Sure I could pay premium for express service but I’ve got plenty of other projects to keep me busy. Stay tuned for updates on this project as the boards ship!